JP2588285B2 - Centering method and centering machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a centering method and a centering method for finishing an outer peripheral portion of an optical material such as a lens and a prism to a predetermined shape, that is, a centering diameter. About the machine.

[Prior Art] Centering processing includes centering of an optical material and grinding of the outer peripheral portion thereof.

Conventionally, in this type of centering machine, a pair of bell clamp holders for holding a lens, which is a workpiece, are supported by bearings, respectively, while a cutting cam having a spark-out portion as a means for setting a cutting amount of a grinding stone. Is arranged on a table that can reciprocate in the cutting direction of the whetstone.
A driving means for moving and stopping the table was provided.

In the centering process, the workpiece is mounted on a pair of bell clamp holders, the start button is pressed to set the cutting start point of the cutting cam (rotary cam) at the processing start position, and then the motor for rotating the grinding wheel is rotated. Then, the motor for rotating the workpiece and the workpiece are started, and both the grindstone and the workpiece are forcibly rotated. Thereafter, the table is moved by the driving means in the direction of increasing the depth of cut by a predetermined distance, and processing is started. The time of spark-out starting from the point when the grinding wheel is pressed against the workpiece by the spark-out portion of the cutting cam as the processing proceeds is set based on the intuition of the operator based on the trial processing. When the spark-out time set by the intuition elapses, the driving means automatically moves the table in the direction of decreasing the cutting amount, and retreats the grindstone from the workpiece and separates it.

[Problems to be Solved by the Invention] In the above-described conventional centering machine, since the spark-out time is set according to the operator's intuition, the spark-out time varies, and the spark-out time is set to an appropriate time. If the length is shorter than this, the centering allowance to be ground originally is not sufficiently ground, and the centering diameter, that is, the outer diameter of the product becomes large. On the other hand, if the spark-out time is longer than the appropriate time, wasted time is wasted, resulting in a variation in the centering diameter of the product, resulting in poor product yield,
There is a disadvantage that the cost is high.

The present invention has been made in view of the above problems,
An object of the present invention is to provide a centering method and a centering machine which do not cause variation in the centering diameter of the product, improve the yield of the product, reduce the cost, and are excellent in mass productivity.

[Means for Solving the Problems] According to the centering method of the present invention, which achieves the above object, an optical material as a workpiece is sandwiched between a pair of centering holders and forcedly rotated, and a grinding wheel which is forcibly rotated is cut. Grinding is performed by pressing against the workpiece by the amount setting means, and in the centering method of performing spark-out in the latter half of the processing, a displacement amount in a direction perpendicular to the axial direction of the centering holder is detected, When the displacement amount at the time of the spark-out reaches zero, the cutting amount setting means is moved in the direction of decreasing the cutting amount of the grindstone to separate the grindstone from the workpiece.

On the other hand, the centering machine of the present invention comprises a pair of centering holders for holding an optical material as a workpiece and forcibly rotating the same, and a cutting amount setting means for moving the forcibly rotating grindstone in the cutting direction. Wherein the cutting amount setting means is provided on a supporting means which is reciprocated in the same direction as the cutting direction by a driving means, wherein the displacement in a direction perpendicular to the axial direction of the centering holder is provided. A displacement measuring device for detecting the amount, a command for inputting a detection value of the displacement measuring device, and when the detection value at the time of spark-out reaches zero, the cutting amount setting means moves in the direction of decreasing the cutting amount of the grindstone. Is output to the driving means of the supporting means.

It should be noted that spark-out in the specification means that even when the cutting setting is zero, the cutting can be performed by the elastic deformation return of the spindle shaft due to the grinding load.

[Operation] Since the processing method and the processing machine of the present invention are configured as described above, when the spark-out in the latter half of the processing is started, the cutting amount of the grindstone becomes constant, so the displacement amount of the centering holder, that is, The displacement of the workpiece gradually decreases. The amount of displacement of the centering holder is detected during this time, and when the detected value, that is, the amount of displacement of the workpiece reaches zero, by moving the cutting amount setting means in the direction of decreasing the cutting amount of the grindstone, the grindstone is processed. Retreat away from an object.

Example Next, an example of the present invention will be described with reference to the drawings.

First, an example of a centering machine used for carrying out the method of the present invention will be described.

In FIG. 1 and FIG. 2, a pair of bell clamp holders 2, 3, which are centering holders having clamp portions 2a, 3a and shaft portions 2b, 3b, respectively, have shaft portions 2b, 3b having bearings 4a, 4b, respectively. It is rotatably supported by the main body 18 via the.
The lens 1 to be processed is a pair of bell clamp holders.
The two spheres of curvature are sandwiched between 2 and 3.
And the axes of the bell clamp holders 2 and 3 coincide with each other. The shaft portions 2b and 3b of the above-mentioned bell clamp holders 2 and 3 are connected to an output shaft of a workpiece rotation motor (not shown) via a drive mechanism (not shown). By starting, the lens 1 and the bell clamp holders 2 and 3 can be integrally rotated around the optical axis. On the other hand, the plate-shaped table 6 as a support means is supported by two guide rails 5a and 5b extending in the direction of the arrow X perpendicular to the direction of the optical axis so as to be movable in the direction of the arrow X. Two guide rails 11a and 11b extending in the arrow X direction are fixed to a part of the upper surface of the table 6. A plate-shaped motor table 12 is supported by the two guide rails 11a and 11b so as to be movable in the direction of arrow X. On the upper surface of the motor table 12, a grinding wheel 8 is detachably mounted on an output shaft 7a. The motor 7 for rotating the grindstone attached to is fixed. The cutting direction of the grindstone 8 is the direction of the arrow X, and the axis of the grindstone 8 and the optical axis of the lens 1 are parallel. Further, a cam rotation step motor 10 is fixed to a part of the upper surface of the table 6 described above. A cam shaft of a cutting cam (rotating cam) 9 having a spark-out portion 9a is detachably attached to an output shaft 10a of the stepping motor 10 for cam rotation. Is in contact with Meanwhile, table 6
On one side surface, the other end of a piston rod 15 having one end fixed to a piston 14 in a hydraulic cylinder 13 fixed to a main body 18 is fixed. It can move back and forth in the direction.
The hydraulic cylinder 13 is provided with a check valve with a variable throttle 25a, 25
b, 4-port 3-position directional control valve 24 having pilot check valves 26a, 26b and two electromagnetic solenoids 24a, 24b
The hydraulic pressure source 25 is connected via a hydraulic tank 19, a hydraulic pump 20, and the hydraulic pump 20.
, A relief valve 22 and an oil pressure gauge 23. On the other hand, the eddy current type non-contact displacement measuring device 16 has a measurement surface fixedly supported on a main body 18 via a member (not shown) so as to face the shaft portion 2b of the bell clamp holder 2, and the shaft portion 2b
The amount of displacement in the direction perpendicular to the axial direction of is detected. The controller 17 includes electronic solenoids 24a and 24b of the directional control valve 24.
Is switched to an energized state or a non-energized state, and the displacement detected by the non-contact displacement measuring device 16 is input. When the displacement at the time of spark-out reaches zero, the direction switching valve 24 is switched off.
By turning on the electromagnetic solenoid 24b, the piston 14 is moved in the direction of decreasing the cutting amount of the grindstone 8 (in the direction of arrow Z).
, The table 6 is moved in the direction of the arrow Z, and the grindstone 8 is retracted from the lens 1 and separated therefrom.

As is clear from the above description, the guide rails 11a, 11
b, a cut amount setting means is constituted by the motor table 12, the cut cam 9, and the cam rotation step motor 10,
On the other hand, the hydraulic cylinder 13, the piston 14, the piston rod 15, the direction switching valve 24, and the hydraulic pressure source 25 constitute driving means for the table 6 which is a supporting means.

Next, the operation of this embodiment, that is, the processing method will be described.

First, the lens 1 is clamped between the two bell clamp holders 2 and 3 at such a pressure that the clamp portions 2a and 3a are not deformed, and the centering is performed. Thereafter, a motor for rotating the workpiece (not shown) is started, and the lens 1 is forcibly rotated at a rotation speed of about 5 rpm. At this time, since no radial load acts on the lens 1, the amount of displacement detected by the non-contact displacement measuring device 16 is zero. Thereafter, when an operation button (not shown) is turned on, the controller 17 outputs a command to the stepping motor 10 for cam rotation to set the cutting start point O of the cutting cam 9 at the machining start position. further,
The controller 17 is an electromagnetic solenoid of the directional control valve 24.
By turning on 24a, the table 6 is moved by a predetermined distance in the direction of increasing the cutting amount (the direction of the arrow Y) until the grinding wheel 8 comes into contact with the lens 1, and at the same time, the grinding wheel rotating motor 7 is started. The grindstone 8 is forcibly rotated at a rotation speed of about 3000 to 5000 rpm. Next, a working fluid (not shown) is supplied to the contact portion between the lens 1 and the grindstone 8, and the cam rotation step motor 10 is started to rotate the cutting cam 9 in the direction of arrow n at a rotation speed of about 3 to 6 rpm. Then, cutting is started, and one cycle of processing is performed.

The processing of this one cycle will be described with reference to FIGS. 3 and 4 as well. Immediately before processing, that is, immediately before cutting, no load is applied to the lens 1 in the radial direction.
The displacement of the shaft 2b detected by the non-contact displacement measuring device 16 is zero. When the cut in which the cut amount is proportional to the time t is started, the displacement amount initially increases sharply and then is kept substantially constant. Then, in the spark-out after the end of the cut, since the cut amount is constant, the non-contact displacement measuring device 16 is used.
, Ie, the displacement of the lens 1 decreases and becomes zero at d '. At this time, the controller 17
The table 6 moves in the direction of the arrow Z by moving the piston 14 in the direction of the arrow Z and stopping it in the initial state by turning on the electromagnetic solenoid 24b of the direction switching valve 24, and the grinding wheel 8 Retreat away from and leave. Thereafter, the controller 17 controls the stepping motor 10 for cam rotation.
To set the cutting start point O of the cutting cam 9 at the machining start position. The spark-out portion 9a of the cutting cam 9 is formed in consideration of the maximum spark-out time.

In the above embodiment, the hydraulic cylinder 13, the direction switching valve 24, and the like are used as the driving means of the table 6.
However, the invention is not limited to this, and a device including a pneumatic cylinder and a direction switching valve, or an electric cylinder or an electric linear motor may be used.

Further, in the above embodiment, the motor table 12, the cam rotation step motor 10, the cutting cam 9 and the like are used as the cutting amount setting means, but the invention is not limited to this. That is, the grinding wheel rotation motor 7 is fixed to the table 6 without using the cam rotation step motor 10 and the cutting cam 9, and the cutting position of the grinding wheel 8 is set by adjusting the moving position of the table 6 by the hydraulic cylinder 13. It may be something.

[Effect of the Invention] Since the processing method and the processing machine of the present invention are configured as described above, when the displacement amount of the workpiece reaches zero, the spark-out is terminated and the spark-out time is set to an appropriate value. As a result, the centering diameter of the product can be finished to an appropriate value, the unevenness of the centering diameter does not occur, and as a result, the product yield is improved, the cost of the product can be reduced, and the mass productivity is excellent. To play.

[Brief description of the drawings]

FIG. 1 is a top view showing a part of an embodiment of the centering machine of the present invention in section, and FIG. 2 is a schematic side view of FIG. 1 showing a state immediately before the start of machining. The figure shows 1 in this embodiment.
FIG. 4 is a graph showing the relationship between the time in the machining cycle and the displacement of the shaft portion 2b, and FIG. 4 is a graph showing the relationship between the time and the amount of cut in one machining cycle in this embodiment. 1… Lens, 2,3… Bell clamp holder, 2a, 3a…
Clamp part, 2b, 3b… Shaft part, 5a, 5b, 11a, 11b… Guide rail, 6… Table, 7… Motor for grinding wheel rotation, 7a
…………………………………………………………………………………………………………………………………………………………….
3 ... Hydraulic cylinder, 14 ... Piston, 15 ... Piston rod, 16 ... Non-contact displacement measuring device, 17 ... Controller, 18
…… Main body, 19 …… Hydraulic tank, 20 …… Hydraulic pump, 21…
... Electric motor, 22 ... Relief valve (regulator), 23 ...
Hydraulic gauge, 24… Directional switching valve, 24a, 24b… Electromagnetic solenoid, 25… Hydraulic pressure generating source, 25a, 25b… Variable check check valve (speed controller), 26a, 26b… Pilot check valve ( Check valve),

Claims (2)

(57) [Claims] An optical material as a workpiece is sandwiched between a pair of centering holders and forcibly rotated, and a grinding wheel which is forcibly rotated is pressed against the workpiece by a cutting amount setting means to perform grinding. In the centering method of performing spark-out in the latter half, the amount of displacement in a direction perpendicular to the axial direction of the centering holder is detected, and when the amount of displacement at the time of spark-out reaches zero, the amount of cut is set. A centering method comprising: moving a means in a direction of decreasing a cutting amount of a grindstone; and separating the grindstone from a workpiece. 2. A cutting device comprising a pair of centering holders for holding an optical material to be processed and forcibly rotating the same, and a cutting amount setting means for moving a forcibly rotating grindstone in a cutting direction. The setting means is a displacement measuring device for detecting a displacement amount in a direction perpendicular to the axial direction of the centering holder in a centering machine arranged on a supporting means reciprocated in the same direction as the cutting direction by the driving means. When the detected value at the time of spark-out reaches zero, a command to move the cutting amount setting means in the direction of decreasing the cutting amount of the grindstone is issued by driving the support means. A centering machine comprising a controller for outputting to a means.